for an inhibitor I either use Surface Shield (
https://blasterproducts.com/product/surface-shield/ ) or Fluid Film (
https://www.fluid-film.com/ )
For rust TREATMENT, I've switched over to exclusively using Corroseal (
https://corroseal.com/ )
To paint over treated rust, I use KBS Rust Seal (
https://www.kbs-coatings.com/rustseal.html )
Por15 is an old technology product, good when used correctly, but not great and has been surpassed by competitors.
I grew up on a Gulf Coast ranch and live on the gulf coast, it's a constant battle with corrosion.